Better debugging for memory killer middleware

This adds more info to the warning messages output by MemoryKiller.

Previously only the PID was showed, making it difficult to debug issues like https://gitlab.com/gitlab-org/gitlab-ce/issues/19124

This adds the worker class and job ID to the log messages.

/cc @pcarranza

Reassigned to @rymai

@rymai feel free to review this - should be a quick one. It's not a regression but it will help debug other regressions so I would suggest to add it to the next 8.9 release...

@jameslopez LGTM (I've retried the failed specs as they don't seem related), thanks!

Enabled an automatic merge when the build for a7b1b512 succeeds

Added ~149423 label

@rspeicher I'd say no CHANGELOG needed for this (internal change).

mentioned in issue gitlab-com/infrastructure#147 (closed)

what's going on with the tests 😓

trying merging with master again...

Added 65 commits:

• a7b1b512...7ca36859 - 64 commits from branch master
• e69af6d2 - Merge branch 'master' of gitlab.com:gitlab-org/gitlab-ce into fix/sidekiq-mem-killer-debug

@jameslopez Tests wer broken due to newly added tags to the gitlab-test repo. They are now removed so retrying the failed tests should work. See https://gitlab.com/gitlab-org/gitlab-ce/issues/19230 for more information.

thanks @razer6 I did retry a few times with no success. Anyway just did another merge and hopefully it should be fine 👍

Enabled an automatic merge when the build for e69af6d2 succeeds

mentioned in commit 3659992c

Status changed to merged

mentioned in issue #19245 (closed)

Removed ~149423 label

Picked into 8-9-stable, will be in 8.9.3.

mentioned in issue #18048 (closed)

mentioned in commit 53452ef5